Field of the Invention
The present invention relates to a motion controller, and in particular, relates to a motion controller capable of customizing a highly responsive command to a motor by a higher-level control device.
Description of the Related Art
In a motion controller performing adaptive control by a command from a higher-level control device, high responsiveness to feedback information of a sensor is needed. To improve the responsiveness, speed up of a communication cycle between the higher-level control device and a controller or speed up of a cycle, in which a command calculated by the higher-level control device based on the feedback information (position or speed) is reflected to a motor, is carried out.
FIG. 5 is a functional block diagram of a motion controller of a conventional art. A motion controller 10 of the conventional art is connected to a higher-level control device 20 by a communication unit performing real-time communication using EtherCAT or others, and receives a motor control command by a communication control part 11 in the motion controller 10, the motor control command being transmitted from the higher-level control device 20. Then, based on a value of the received motor control command, the motion controller 10 updates motor control information used for controlling a motor 2, the motor control information being stored in a motor control information storage part 13 provided on a not-shown memory. The motor control information stored in the motor control information storage part 13 is inputted to an axis control part 12, and the axis control part 12 controls an amplifier 3 based on the inputted motor control information, to thereby drive the motor 2 attached to a machine to be controlled. Moreover, a value of a sensor 5 attached to the machine to be controlled is inputted to the higher-level control device 20 by the communication control part 11. Note that the higher-level control device 20 is connected to an operating panel or others of the machine via an I/O unit 30, and thereby receives operation onto the operating panel by an operator.
FIG. 6 is a diagram showing an example of controlling the machine by the motion controller and the higher-level control device of the conventional art. Note that, in FIG. 6, partial illustration, such as the motor control information storage part 13, is omitted. The higher-level control device 20 includes a command calculation processing part 21 that creates a motor control command to direct a target position or the like of the motor 2, and the command calculation processing part 21 is connected to the communication control part 11 provided to the motion controller 10.
The axis control part 12 controls the amplifier 3 in response to the value of the motor control information, such as a moving amount or a torque limit, to thereby drive the motor 2. From the higher-level control device 20 to the motion controller 10, the target position is successively transmitted by the motor control command, and converted into the moving amount of the motor control information and inputted to the axis control part 12; accordingly, the motor 2 is operated to follow the inputted target position by performing positional control.
In the machine to be controlled by the higher-level control device 20 and the motion controller 10, there is a mechanical part 4 driven by rotation of the motor 2, and moreover, in an operating range of the mechanical part 4, a processed part 6, to which a pressure sensor 5a is attached, is placed, to thereby try to perform a pressing operation with a constant pressure.
When the motion controller 10 of the conventional art is used in controlling such a system, in accordance with a value of sensor information detected by the pressure sensor 5a, the command calculation processing part 21 of the higher-level control device 20 calculates the target position and the torque limit of the motor as the motor control command. The motion controller 10 converts the target position of the received motor control command into the moving amount per, for example, encoder unit of the motor control information, and regards the moving amount as an input to the axis control part 12.
However, if the motor control command and the motor control information have the same definition, the conversion may not be carried out.
Note that, as a conventional art for achieving high responsiveness, for example, in the technique disclosed in Japanese Patent Laid-Open No. 2013-73351, multiple-divided control computing portions according to characteristics of respective axes of a control device are distributed to a servo amplifier or a servo controller, to thereby increase control responsiveness in servo control.
However, in the control of the motor by the motion controller of the conventional art, since the measurement value of a sensor is fed back to the higher-level control device, and the command to the motor is changed by use of the value, it was difficult to improve responsiveness of the entire system due to communication delay. For instance, in the example of FIG. 6, if the higher-level control device 20 monitors the value of sensor information detected by the pressure sensor 5a and fed back to the motion controller 10 and performs control of the motor 2, the responsiveness with respect to fluctuation in the pressure value is deteriorated due to the influence of delay in communication time between the higher-level control device 20 and the motion controller 10. Moreover, if a process using the sensor information is incorporated into the axis control part 12 for improving the responsiveness, the higher-level control device 20 can merely select a control method to be executed from those incorporated into the axis control part 12, and thereby a problem of reducing flexibility in control occurs.
Moreover, by applying the technique disclosed in Japanese Patent Laid-Open No. 2013-73351 to the motion controller 10, it is possible to perform part of the servo control incorporated into the motion controller 10 in high-speed cycle; however, it is impossible to improve responsiveness of the process calculating the command of the position or speed performed by the higher-level control device 20.